1) Field of the Invention
The present invention relates to an image display control unit, image display control method, image displaying apparatus, and image display control program recorded computer-readable recording medium, suitable for use in an image displaying unit such as a portable terminal unit (PDA: Personal Digital Assistant) which displays an image on a small-sized display screen.
2) Description of the Related Art
In the recent years, portable information equipment reduced in size and weight have come into widespread use. These portable information equipment are provided with a small-sized display screen such as a liquid crystal display (LCD), and a user puts an image, stored in a storage device or the like in such portable information equipment, on a display screen for various purposes, such as for reading.
At this time, the user manipulates an operating button, a touch panel or the like on the body of the information equipment for selecting a desired image from a plurality of images stored in advance or for enlarging/reducing the image selected in this way on the display screen to display a desired portion of the image. Moreover, in such information equipment, an image display control unit is made to control the display of image data onto the display screen.
Meanwhile, such a conventional image display control unit is designed to make image reduction/enlargement display at predetermined magnification, for example, ⅛ size, ¼ size, half size, equal size, double size, four-times size and eight-times size, with respect to an image displayed on the display screen. For this reason, in order to put the image on the display screen in an easy-to-see condition, the user is required to press the operating button several times for adjusting the display magnification while repeatedly conducting the enlargement/reduction. This is troublesome to the user.
In addition, in displaying a rectangular image with a large aspect ratio on the small display screen of the portable information equipment, it is preferable that the image display is made to avoid a wasteful use of the display screen.
Still additionally, in displaying an image including characters on the display screen, an operating button or the like is pressed to adjust the display magnification while repeatedly conducting the enlargement/reduction so that the characters appear in an easy-to-see condition on the display screen. This is also troublesome.
Moreover, there has been known a method in which an index image produced by reducing image data is displayed on the display screen and switched successively to retrieve and select an image undergoing editing or the like. FIGS. 14A and 14B are illustrations useful for explaining index display in a conventional image displaying apparatus. FIG. 14A is an illustration for describing a key manipulating manner for index image switching, while FIG. 14B is an illustration of an example of an index image displayed on a display screen.
In the conventional displaying apparatus, in a state where an index image is displayed on a display screen as shown in FIG. 14B, a user selectively shifts an index image switching key in right/left directions as shown in FIG. 14A so that the index image is switched to another index image on the display screen.
In addition, in the conventional image displaying apparatus, the index image is made to appear on the display screen in a condition reduced to the extent that the contents of the image is understandable. The user presses the index image switching key while seeing the index image displayed on the display screen to successively switch the index image, and presses a selecting button (not shown) when a desired index image appears on the display screen. Thus, the user can see the detail of that image.
However, there still exist requirements for the improvement of convenience in displaying such an index image on the display screen.